The invention relates to lubrication of a bearing and more particularly to dispensing a lubricant entrained in a gas into the bearing to lubricate the bearing. The invention is disclosed in the context of lubricating a bearing of a gas turbine engine. The invention is believed to be useful in other applications as well.
Lubrication systems for application to rotary elements, such as bearings, are known. See, for example, U.S. Pat. Nos. 2,986,433; 3,004,806; 4,502,274; 4,621,710; 5,113,818; 5,207,291; 5,251,725; 5,301,771; 5,404,964; 5,439,361; 6,098,583. The disclosures of those references are hereby incorporated herein by reference. No representation is intended that a complete search has been made of the prior art or that no better art than that listed is available, and no such representation should be inferred. This listing shall not be construed to be an admission that the listed references are, or are considered to be, material to patentability.
Some lubrication systems use gas-entrained lubricant to lubricate bearings coupled to a shaft. For example, mist lubrication systems use gas-entrained lubricant but are generally limited to applications characterized by a Dn value of less than or equal to 2.0 million millimeters-revolutions per minute (or mm-rpm), wherein Dn is defined as the product of the bearing bore diameter measured in millimeters and the angular velocity of the shaft measured in revolutions per minute. This is because rotation of the bearing and the shaft in Dn applications above 2.0 million mm-rpm induces a chaotic, turbulent flow field adjacent the bearing, thereby threatening ingress of low-momentum, gas-entrained lubricant particles into the bearing. Thus, it is desirable to have a lubrication system configured to lubricate a bearing using gas-entrained lubricant in high Dn applications above 2.0 million mm-rpm.
A lubrication system is disclosed herein for use with a bearing comprising an outer race, an inner race, and bearing elements disposed therebetween. Rotation of the bearing and a shaft journaled thereby about a central axis induces air movement having a first air velocity and a path adjacent the bearing. The lubrication system comprises a structure providing a passageway through which gas-entrained lubricant is delivered at a second velocity to the bearing and a flow modifier disposed relative to the bearing and the structure to modify the first air velocity to promote movement of the lubricant into the bearing.
In illustrative embodiments, the lubrication system further comprises a lubricant dispenser configured to dispense gas-entrained lubricant through an outlet into the bearing. The flow modifier is configured to slow the first air velocity relative to the velocity of the gas-entrained lubricant so that the gas-entrained lubricant dispensed from the outlet reaches the bearing to lubricate the bearing. The flow modifier comprises a screen structure comprising first baffles arranged in series about the shaft and a pair of second baffles coupled to at least one of the first baffles. The second baffles cooperate to define a space therebetween in which the outlet is disposed.
The present invention comprises, therefore, a screen structure disposed adjacent a bearing to modify the induced air flow. Illustratively, the screen structure will slow the induced air flow. Preferably, the screen structure will slow the induced air flow so that the velocity of the induced air flow is less than or equal to the velocity of the gas-entrained lubricant. The screen structure is provided with spaces into which nozzles are disposed. The nozzles are configured to dispense the gas-entrained lubricant onto the inner race of the bearing. The first baffles are disposed in the flow field of the induced air flow and are provided with a plurality of apertures through which the induced air movement can flow.
Illustratively, each second baffle comprises a base provided with a plurality of apertures through which the induced air movement can flow and a tang coupled to the base and extending toward the bearing. In illustrative embodiments, each tang is configured to block the flow of the induced air movement through the tang. In other illustrative embodiments, each tang is provided with a plurality of apertures through which the induced air movement can flow. Each nozzle is disposed between a pair of tangs.
Additional features and advantages of the infant care unit will become apparent to those skilled in the art upon consideration of the following detailed descriptions exemplifying the best mode of carrying out the apparatus as presently perceived.